This invention relates to a slide ring seal assembly which may find particular use for sealing pump shafts and which is of the type that has an axially shiftable slide ring, an elastic collar surrounding the shaft and serving for statically sealing the slide ring with respect to the shaft and a compression spring which concentrically surrounds the shaft and which serves for axially pressing the slide ring against a counter ring. The compression spring is frictionally connected with the shaft by means of at least one spring wire turn at the end opposite from the slide ring.
A slide ring seal of the above-outlined type which is disclosed, for example, in French Pat. No. 1,241,626, has an axially shiftable and rotatable slide ring, an approximately conically wound compression spring surrounding the shaft and acting in the axial direction by pressing the slide ring axially against a counter ring. In the zone of the spring wire turns which have the smallest diameter, the compression spring is adapted to the diametral dimensions of the shaft and at that location the spring is frictionally connected with the shaft in a torque-transmitting manner and abuts a shaft collar for axial support. The static seal between the slide ring and the shaft to hermetically separate a pressure chamber from the environment is effected by an elastic ring which is received in a recess in the reverse side of the slide ring and which is tightened about the shaft. An additional cover disc on the free end faces of the slide ring constitutes a spring support for the spring for exerting pressure on the slide ring.
While slide ring seals of the above-outlined construction have been used for many years, their manufacture has still been expensive and complicated. Thus, the slide ring seal has been formed of at least four components which all have to be separately manufactured and assembled to a structural unit. The slide ring which preferably is made of a hard and wear-resistant sintered material may be sintered only if it is of relatively large volume so that the final contours and recesses have to be machined into the hard material by a subsequent operation.
In the slide ring seal disclosed in French Pat. No. 1,241,626 a transmission of the torque from the shaft to the slide ring is effected exclusively by the compression spring by providing that the latter is, on the one hand, attached by friction to the shaft and abuts a shaft collar and, on the other hand, is pressed with its end face against the free end face of the slide ring. Particularly in case of tolerance deviations in the finished spring and a weakening of the spring force after a long service period, an unsatisfactory torque transmission may occur--particularly in case of high loads on the slide ring seals--which manifests itself by a circumferential slippage of the spring with respect to the slide ring seal components. This results in friction-caused wear of the spring and the ring components, and the entire seal may lose its sealing properties and has to be eventually replaced at significant expense.